Build and Deploy Your Own AWS Lambda Functions from Scratch in Ruby

You've been building Ruby applications for years. You love the language, the ecosystem, the elegance of Rails. But at some point, the infamous buzzwords start making an appearance: "microservices," "serverless", "Lambda functions", "event-driven systems". Everyone starts talking about "modernizing our stack for better scalability and cost savings."

That familiar knot forms in your stomach. You know what's coming next: "We'll probably need to write this new feature in Node.js or Python." Suddenly, you're wondering if your Ruby skills are becoming outdated. Are you falling behind? Will you be competitive in the job market if you don't learn these new languages? Is the world passing you by while you're still writing Ruby?

Sound familiar?

I've been there. Sometimes it feels like the entire world is declaring that Ruby "just isn't keeping up with modern cloud development." Watching as teams abandon years of Ruby expertise to chase the latest JavaScript framework du jour. Seeing perfectly good Ruby codebases become abandoned, dismantled and rewritten as Python or Node.js "microservices".

It doesn't have to be this way.

Let me share something that might surprise you. Last month alone, the Ruby Lambda functions I've written have processed tens of millions of events, files and API requests. These functions are now handling parts of systems that were completely unscalable using a traditional Rails app; massive data ingestion, parallel file processing, and real-time event handling that was previously causing major bottlenecks.

You don't need to learn a new language.
You don't need to rewrite your Rails application.
You don't need to throw away years of Ruby knowledge.

What you need is a shortcut through months of trial and error. A system that gets you from idea to deployed Lambda function in hours, not weeks of debugging obscure AWS errors.

Here's what most Ruby developers get wrong about serverless:

They think serverless means throwing away their Rails application and rewriting everything as microservices. They believe they need to abandon their monolith and break it into dozens of tiny Lambda functions. They assume that "going serverless" means starting over from scratch.

This couldn't be further from the truth.

The real power of serverless Ruby isn't replacement, it's amplification.

Your Rails application should stay exactly where it is. But imagine being able to offload your heaviest processing tasks to Lambda functions that scale infinitely and cost pennies. Picture having your Rails app trigger serverless workers that can process thousands of files in parallel, generate complex reports in the background, or handle massive data imports without blocking your main application.

That's when Ruby becomes a serverless powerhouse, not when you replace Rails, but when you supercharge it.

I'm not going to lie to you, it can be hard on your own.

AWS documentation is scattered and mostly focused on Node.js and Python examples. The Ruby ecosystem has limited guides on serverless tooling. Stack Overflow is full of outdated advice. You'll spend weeks just figuring out the basic setup, let alone building something production-ready.

I know because I've been there. I've burned countless hours debugging issues, wrestling with configurations, and figuring out why my functions randomly aren't working. I've made every mistake in the book so you don't have to.

That's exactly why I wrote this guide.

This Serverless Ruby guide isn't just theory, it's battle-tested knowledge from someone who's built real systems that handle real traffic. Inside, you'll find the exact Terraform and Docker configurations I use, and re-usable code templates that will cut your deploy time from days to minutes.

You'll build actual ETL pipelines that ingest CSV data from S3 and send results to your Rails application. You'll create Lambda functions that your Rails app can invoke for heavy data processing. You'll master event-driven architecture with tools like SQS, Kinesis, and API Gateway.